There are a number of useful procedures for introducing implants into open regions of the human body, e.g., aneurysms, for the purpose of closing that region. Various interventional procedures using catheters deliver occlusive wire coils, detachable balloons, or coagulative or glue-like substances into a variety of body regions. For instance, it is common to control internal bleeding or to fill aneurysms with such devices or materials so to limit the flow of blood or to lessen contact of the aneurysm wall to the blood pressure. It is also common to use such procedures in restricting the flow of blood to tumors.
Delivery of vasoocclusive coils through various catheter delivery systems is a complicated task, particularly when the coil has both a linear primary shape and a convoluted secondary shape once it is ejected from the tip of the catheter. Vasoocclusive coils having secondary shapes are used for a variety of reasons. Such coils present multiple surfaces to the blood so to cause the formation of embolus. Further, a coil having a properly shaped secondary configuration will engage the wall of the vessel and anchor the coil in place. Long coils assuming a random configuration once ejected from the catheter are also known. Although these long, randomly oriented secondary shape coils are quite good at presenting fresh thrombogenic surfaces and hence easily form thrombi, there is a trade-off to be accounted for. Should the coil be of the wrong size or be mal-placed, such long coils are difficult to reposition or to remove. Consequently, it is sometimes desirable to use a coil having a smaller amount of metal but with a more calculated shape so to allow easy removal or re-placement while still readily forming thrombus. Furthermore, shorter coils exhibit less friction when being pushed through a catheter lumen. Such improved friction characteristics allows placement of coils in more distal vasculature, such as found in the brain, than other longer, higher friction devices. The devices described herein are suitable for forming thrombus and yet may be readily removed or repositioned as needed.
There are a number of known vasoocclusive devices having secondary shapes.
One such device may be found in U.S. Pat. No. 4,994,069, to Ritchart et al. Ritchart et aI. describes a variety of regular and random secondary shapes for vasoocclusive devices which may be ejected from the distal tip of an intravascular catheter. A conical device is shown in the FIG. 5.
U.S. Pat. Nos. 5,122,136 and 5,354,295, both to Guglielmi and Sepetka, describe vasoocclusive coils having secondary forms which are "cylindrical or conical" at column 6, lines 23-34. These coils are used to provide support for emboli formed in various vascular cavities of the body.
Another conical vasoocclusive coil is shown in WO95/25480, to Tekulve.
U.S. Pat. No. 5,334,210, to Gianturco, describes a vascular occlusion assembly. The assembly is made up of a foldable material occlusion bag having an expanded diamond shape and an elongated flexible filler member which is inserted into the internal cavity of the occlusion bag. The filler member is apparently typically a helically wound coil which is introduced into and ultimately is designed to fill the occlusion bag.
None of the prior art discussed above discloses any of the variations of the inventive vasoocclusive device described below.